For various reasons crops sometimes are lying so close to the ground that it is difficult to cut them with a conventional harvest header. Some crops are inherently short, while others may be taller, but are prone to fall down when they reach maturity. Heavy rain, wind, or hail can also cause crop stalks to be lying close to the ground at harvest time.
Typically the knife on cutting headers comprises a knife bar extending along the front lower edge of the header, with a plurality of triangular knife sections attached to the bar such that the apex of the triangle extends forward from the bar. The exposed side edges of the knife sections are sharpened. Guards are attached to the front lower edge of the header and serve to protect the knife sections from breakage when contacting stones and like obstructions. The guards comprise pointed guard fingers extending forward, and the knife moves back and forth along the edge of the header in a slot cut laterally through the guard fingers. In addition to protecting the knife, the guard fingers also enable the knife sections to cut the crop. As the knife section moves back and forth it pushes crop against the sides of those portions of the guard finger that are above and below the slot, shearing the crop stalks.
A conventional knife is a few inches above the ground when the header is in its lowest position, such that very short or downed crop material will pass under the knife and be lost. Many different kinds of “crop lifters”, as they have come to be known, have been developed over the last century and more. Typically these crop lifters are attached to the header and/or the forward extending point of the guard finger, and provide an arm of various designs that rides along the ground ahead of the knife. A lifting finger extends at a shallow angle from the front of the arm back and over the knife. As the header moves down the field, the arm rides along the ground and under the downed crop stalks, which then are lifted and pass over the lifting finger to the knife, where they are cut and continue moving onto the header from where they can be passed to the harvester, swather table, or the like.
A problem with providing mounts for attaching crop lifters to harvest headers is that the angle with respect to the ground of the various headers made by different manufacturers is different, and so mounting the crop lifter so that the lifting fingers and skid portions address the ground at a suitable angle is problematic, often requiring providing different mounting brackets for different brands of headers.
U.S. Pat. Nos. 700,029 and 791,022 to Gatermann, U.S. Pat. No. 2,734,332 to Fisher, U.S. Pat. No. 2,892,298 to Chaney, U.S. Pat. No. 2,141,299 to Hume, and U.S. Pat. No. 723,880 to Koch disclose such a crop lifter that is pivotally attached to the header so as to be able to move up and down to follow the ground. The Fisher device floats on the ground, while the others are biased toward the ground by springs. The Hume and Koch lifters include a mechanism for limiting the range of pivotal movement. U.S. Pat. Nos. 4,120,138 and 6,691,499 to Schumacher illustrate a crop lifter that is fixed to the header instead of pivoting, but is made of spring steel so that same may move up and down to follow the ground. The crop lifter shown in Schumacher's U.S. Pat. No. 6,691,499 patent includes a mechanism for incrementally adjusting the downward angle of the crop lifter relative to the header to which it is attached, thus facilitating mounting on headers with different angles.
The above crop lifters include a skid portion that rests on the ground during operation and travel along the ground and moves up and down on a pivot axis or bending spring member, and an upper crop lifting finger extending upward and rearward from the skid portion such that the skid portion runs on the ground under the straws and then the straws ride up and back on the finger and are lifted above the knife such that same can be cut and carried back onto the header.
United States Patent Application Number 2012/0060462 of the present inventor Dietrich discloses an alternate type with no skid portion resting on the ground. The crop lifting finger is attached at a fixed adjustable angle to the front of a guard finger, and slopes upward and rearward from the front end thereof. The front end moves along the field slightly above the ground and contact with the ground is only incidental.
The mechanisms of Schumacher U.S. Pat. No. 6,691,499 and Dietrich 2012/0060462 for adjusting the angle of the lifting finger can compensate for different header angles such that the same crop lifter apparatus can be mounted on headers that are mounted at different angles relative to the ground. The angle adjustment can also address bent mounting brackets by adjusting the angle on bent brackets to be the same as on undamaged brackets. It may also be desirable to change the angle to address varying operating conditions.
It is also desirable with some crop conditions, especially with auger type combine headers, to have the crop stalks fall against the forward side of the auger so the fighting on the auger moves the top of the stalks toward the feeding mechanism in the middle of the header, so the crop stalks enter the feeding mechanism head first, improving feeding. With tall upstanding crops this is naturally accomplished however crop stalks that are laying down are typically lifted by the crop lifters only above the knife, and so slide along the header under the auger.